Electrical connector plugs such as RJ-45 plugs have been used for network applications. These plugs include conductors wherein pairs of conductors are provided for each transmission path. Plugs such as RJ-45 plugs have eight conductors or four pairs for four different transmission lines. These may include a central pair and the split pair. With standard RJ-45 plugs, there exists huge capacitive coupling between the central pair blades and the split pair blades as well as the corresponding twisted-pair leads.
For high speed or high frequency applications capacitive coupling can harm the performance of the plug-jack pair. Capacitive coupling or capacitive reactance is a component of the impedance (Z) of the plug where Z(impedance)=R(resistance)+jX(capacitive reactance+inductive reactance). Capacitive coupling harming the performance is especially due to the arrangement of transmission paths with a central pair of conductors surrounded by a so-called split pair of conductors, namely one conductor on one side of the central pair and another conductor on another side of the central pair being part of one transmission path. Coupling (capacitive reactance) is particularly problematic in the region of the central pair and the split pair at the plug contacts.
Due to the significant capacitive variation caused by the arrangement of regular twisted pairs of wires and adjacent blades, it is difficult to reach the high performance with a regular twisted pairs and blades arrangement. More and more high performance plugs are using a printed circuit board (PCB) to replace twisted pairs to make a connection with the blades. Such blades have mounting and electrical connection pins connecting each blade, with pin mounts, on the PCB which are then connected to individual wires of a cable. In this way, the uncertainty of blades and twisted pair leads are removed. The circuit boards can use additional coupling to increase coupling that occurs at the plug conductors. However, with high frequency applications, namely frequencies increased to 2 GHz, for example, the application of Category 8, the coupling between blades can be no longer treated like a lumped capacitor; rather, they will behave more like coupled transmission lines. That means the couplings are no longer linear regarding the frequency. But the standard (TIA-568-C.2-1) requires a linear behavior of the plug couplings. The problem becomes worse if there are any couplings in the PCB circuits are added on to the blades couplings.